Glycoproteins From Rabdosia japonica var. glaucocalyx Regulate Macrophage Polarization and Alleviate Lipopolysaccharide-Induced Acute Lung Injury in Mice via TLR4/NF-κB Pathway

Abstract

Background and Aims:Rabdosia japonica var. glaucocalyx is a traditional Chinese medicine (TCM) for various inflammatory diseases. This present work aimed to investigate the protective effects of R. japonica var. glaucocalyx glycoproteins on lipopolysaccharide (LPS)-induced acute lung injury (ALI) and the potential mechanism.Methods: Glycoproteins (XPS) were isolated from R. japonica var. glaucocalyx, and homogeneous glycoprotein (XPS5-1) was purified from XPS. ANA-1 cells were used to observe the effect of glycoproteins on the secretion of inflammatory mediators by enzyme-linked immunosorbent assay (ELISA). Flow cytometry assay, immunofluorescence assay, and Western blot analysis were performed to detect macrophage polarization in vitro. The ALI model was induced by LPS via intratracheal instillation, and XPS (20, 40, and 80 mg/kg) was administered intragastrically 2 h later. The mechanisms of XPS against ALI were investigated by Western blot, ELISA, and immunohistochemistry.Results:In vitro, XPS and XPS5-1 downregulated LPS-induced proinflammatory mediators production including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and nitric oxide (NO) and upregulated LPS-induced IL-10 secretion. The LPS-stimulated macrophage polarization was also modulated from M1 to M2. In vivo, XPS maintained pulmonary histology with significantly reducing protein concentration and numbers of mononuclear cells in bronchoalveolar lavage fluid (BALF). The level of IL-10 in BALF was upregulated by XPS treatment. The level of cytokines including TNF-α, IL-1β, and IL-6 was downregulated. XPS also decreased infiltration of macrophages and polymorphonuclear leukocytes (PMNs) in lung. XPS suppressed the expression of key proteins in the TLR4/NF-κB signal pathway.Conclusion: XPS was demonstrated to be a potential agent for treating ALI. Our findings might provide evidence supporting the traditional application of R. japonica var. glaucocalyx in inflammation-linked diseases.

Macrophage Polarization and Its Role in Liver Disease

“…JAK/STAT1 and TLR4/NF-κB pathways are important mechanisms of M1 macrophage polarization, while STAT6 is mainly related to M2 ( 45 , 46 , 91 ). Through the in vivo and in vitro experiments, Xie et al.…”

“…JAK/STAT1 and TLR4/NF-kB pathways are important mechanisms of M1 macrophage polarization, while STAT6 is mainly related to M2 (45,46,91). Through the in vivo and in vitro experiments, Xie et al (92) demonstrated that protein interacting with C kinase 1 up-regulated the expression of STAT6 and p38a as well as inhibited the NF-kB signaling pathway, promoting M2 and inhibiting M1 polarization, which reduced the liver injury.…”

Tetrahydropalmatine induces the polarization of M1 macrophages to M2 to relieve limb ischemia‐reperfusion‐induced lung injury via inhibiting the TLR4/NF‐κB/NLRP3 signaling pathway

“…Activation of toll‐like receptor 4 (TLR4) on lung macrophages induces the nuclear factor‐κB (NF‐κB) inflammatory signaling pathway through leading to the release of downstream inflammatory cytokines including interleukin‐1β (IL‐1β), IL‐6, and tumor necrosis factor‐α (TNF‐α), ultimately causing severe inflammatory damage to lung (Shi et al, 2020). In particular, emerging evidence showed that the TLR4/NF‐κB pathway also played an important role in ALI via regulating macrophage polarization (L. Wu et al, 2019; Ren et al, 2021; R. Li, Shang et al, 2020). Li et al demonstrated that high mobility group protein 1 (HMGB1) induced polarization of M1 macrophages through TLR4‐mediated NF‐κB signaling pathway to regulate LPS‐induced ALI (J. Wang et al, 2020).…”

“…The consistent result was also confirmed by another study, which revealed that a traditional Chinese medicine Rabdosia japonica var. glaucocalyx could regulate macrophage polarization and alleviate LPS‐induced ALI in mice via TLR4/NF‐κB pathway (Ren et al, 2021). The aforementioned studies strongly supported the important role of TLR4/NF‐κB pathway‐mediated macrophage polarization in ALI.…”

“…Additionally, in accordance with in vivo results, THP pretreatment effectively reversed the altered phenotypes of cells when cocultured with rat serum from LIR-ALI model. As a result, our results demonstrated that THP alleviated LIR-ALI both in vivo and in vitro through inducing the polarization of M1 macrophage to M2 phenotype.A growing body of literature has shown that TLR4/NF-κB pathway, a classical proinflammatory signaling, plays an important role in ALI via regulating macrophage polarization (L Wu et al, 2019;Ren et al, 2021;R. Li, Shang et al, 2020)…”